A 7.3-magnitude struck there region overnight, just one day after a 6.2 earthquake forced tens of thousands of people to flee their homes on the island of Kyushu.

Aftershocks continued to rattle southwestern Japan on Saturday after a powerful and shallow 7.3-magnitude quake struck the region overnight. Rescue efforts continued after sunset in the Kyushu region, with emergency personnel digging through the rubble in search of survivors.

According to the Kumamoto prefecture, Kyushu's capital, the most recent quake killed at least 35 people. Just two days earlier, a 6.2 earthquake shook Kyushu, causing tens of thousands of people to flee their homes. The combined toll of both quakes so far is 41, according to the disaster management office. Around 1000 people are reported injured.

After the most recent major quake, hundreds of patients were evacuated from a hospital which seemed close to collapsing. People were, again, forced to flee from their homes.

The earthquake sparked fires in Kumamoto, a city of about 700,000 people.

Television footage showed fires, power outages, collapsed bridges, a severed road hanging over a ravine and gaping holes in the earth. Residents near a dam were told to leave because of fears it might crumble, broadcaster NHK said. The quake also triggered huge landslides, cutting off entire villages.

"I felt strong shaking at first, then I was thrown about like I was in a washing machine," said a Tokai University student who remains isolated in the village of Minamiaso in Kumamoto province on the island of Kyushu.

Rain and cold were forecast overnight, adding extra urgency to the rescue effort.

"All the lights went out and I heard a loud noise. A lot of gas is leaking and while there hasn't been a fire, that remains a concern," the student, who is sheltering in a university gym with 1,000 other students and residents, told Japanese media.

About 190 of those injured were in serious condition, the government said.

Many frightened people wrapped in blankets sat outside their homes while others camped out in rice fields in rural areas surrounding the main towns. About 422,000 households were without water, and about 100,000 without electricity, the government said. Troops were setting up tents for evacuees and water trucks were being sent to the area.

Heavy rain and wind were forecast, with temperature expected to drop to 55 degrees Fahrenheit overnight. Firefighters handed out tarpaulins to residents so they could cover damaged roofs.

"The wind is expected to pick up and rain will likely get heavier," Prime Minister Shinzo Abe told a government meeting. "Rescue operations at night will be extremely difficult... It's a race against time."

Japanese Self Defense Forces personnel in the town of Mashiki, close to the epicenter of the quake, were providing food and water.

"I don't mind standing in line. I'm just thankful for some food," said a man in his sixties waiting for a meal.

Japan is located in the "Pacific Ring of Fire," a horseshoe-shaped region known for its geological activity. About 90 percent of the world's earthquakes and 81 percent of the world's largest earthquakes occur along this region, which is a series of converging plate boundaries and have created oceanic trenches and volcanoes as a result.

In 2011, a magnitude nine earthquake north of Tokyo triggered a devastating tsunami and nuclear meltdown at Fukushima, contaminating water, food and air for miles around. Nearly 20,000 people were killed in the tsunami.

The epicenter of Saturday's quake was near the city of Kumamoto and measured at a shallow depth of six miles, the United States Geological Survey (USGS) said. The shallower a quake, the more likely it is to cause damage.

The USGS estimated that there was a 72 percent likelihood of economic damage exceeding $10 billion, adding that it was too early to be specific. Major insurers are yet to release estimates.

Factories on the island, including electronics giant Sony Corp, and automobile companies Toyota and Nissan, halted production following the quakes. Toyota said there was no discernible damage to its plants but would decide on Sunday whether to reopen.

Chief Cabinet Secretary Yoshihide Suga said nearly 80 people were believed trapped or buried in rubble. Rescuers managed to pull 10 students out of a collapsed university apartment building in the town of Minami on Saturday.

Extra troops are being deployed for rescue efforts. 20,000 additional personnel are expected to arrive on Sunday, as well as additional police, firefighters and medics.

Kyushu is a seismically active, mountainous island, and home to Japan's most active volcano, Mount Aso.